In general, in the case of the supply of municipal water to high-rise buildings and collective residences, municipal water which has been disinfected by chlorine is introduced from a source of water supply into a water storage tank disposed in the ground under a building, and the water in the water storage tank is lifted by a pump to a distribution tank installed on the roof of the building and is distributed through a water distribution system to individual users. The water in the water storage tank is frequently contaminated by various bacteria and microorganisms, and sanitation problem occurs when the water from the water storage tank which is not treated is used as potable water. Chlorine is effective for killing various bacteria and microorganisms contained in the stored water, but it combines with ammonia, producing trihalomethane. Since trihalomethane is a compound causing cancer, the necessity for purifying municipal water before it is used as potable or drinkable water has been increasing recently. Such contaminated municipal water is made to pass through activated charcoal particles or lumps so that contaminants are adsorbed and removed by activated charcoal. In general, since activated charcoal has high adsorbability, it is desirable as a treating agent, but when its adsorptivity is almost saturated, its adsorbability is decreased so that thereafter it does not exhibit capability as a treating agent. Activated charcoal whose adsorptivity has been once decreased as described above cannot be used again unless the activated charcoal is subjected to a regeneration or reactivation treatment for removing adsorbed substances. For this reason, a purification device utilizing activated charcoal has the problem of high running cost, that is, high regenerating cost. In the case of multistory residences or building, the quantity of water to be treated is large so that the quantity of activated charcoal to be used is also large. Consequently, there arises a problem in that when the activated charcoal is packed into a large-sized purification vessel, it is difficult to regenerate the activated charcoal because the gases resulting from the regenerating treatment cannot be completely discharged out of the purification vessel. In addition, there is the problem, when activated charcoal particles are used, of the device inevitably becoming large in size so that a large installation space must be provided.
In view of the above, an object of the present invention is to provide a water purification device which removes adsorbed substances from the surfaces of a large quantity of sheets of activated charcoal cloth whose adsorbing capability has decreased because of the adhesion of the adsorbed substances to the surfaces of the sheets of activated charcoal cloth so that the sheets of activated charcoal cloth can be regenerated and reactivated and that the device can be made compact in size.